For example, I like writing about aliens, the supernatural, werewolves, vampires, all that good stuff. So I'll go to books that have been published that are successful in these subjects and characters. If I get too stuck with the computer all day, I'll go for a walk, or cook something from scratch--a perfect metaphor for building a story. Be present. Don't wait for the muse to come to you, come to her. Offer her little gifts. If you show up at the page, something great is bound to happen.
Feed your creativity. I love to use images, especially "mash-ups" like the one above--a classic painitng with some modern design thrown in, because that's what my chosen genre, urban fantasy, is about. A mixture of past and present, mythology and technology. So I'll feed my brain images like that.
Julia Cameron's advice (from The Artist's Way, pg. 21): "think magic, think delight, think fun. Do no think duty. Do what intrigues you, explore what interests you, think mystery".